Current and historical trends in yields. Of free-base nicotine by Canadian cigarettes in relation to smoke Ph and cigarette design properties
The amount of free-base nicotine (FBN) in tobacco smoke and its relationship to smoke pH and cigarette design continues to be controversial. This study was undertaken to provide both current and historical data in this regard. The sample set consisted of 14 tobacco products including plain, filter-tipped, fine-cut, 120 mm cigarettes and cigarette-sized cigars, plus 7 brands of 'historical' Canadian cigarettes (plain and filter-tipped) purchased at five points in time between 1969 and 2007. Data for payer porosity, tip ventilation pressure drop were obtained using ISO methodologies. Smoke pH was determined using Health Canada method T- 113. Yields of FBN were determined using headspace solid-phase micro-extraction (HS-SPME), combined with gas chromatography/mass spectrometry. With respect to 'current' cigarettes, under ISO smoking conditions (60/30/2 - puff volume, interval, duration) yields of FEN averaged 28.7 µg/cig, (range: 9.46 to 49.1) and were positively correlated with smoke pH (R2 = 0.54). When expressed as a percentage of total nicotine, values ranged from 0.7 to 7.4% (average, 3.4%) and were inversely proportional to both tar yield (R2=0.79) and moisture content of TPM (R2=0.64) but positively correlated with tip ventilation (R2 = 0.88). Under intensive smoking (55/30/2 - 100% vent blocking), yields ranged from 15.7 to 34.1 µg/cig (average 21.2 µg/cig). In this case, the percentage of FBN averaged 0,9% and was independent of tar yield, moisture content and smoke pH. Considering the historical sample set, yields of FBN under ISO smoking conditions averaged 10.6 µg/cig between 1969 and 1993, (range: 5.27 to 18.1 µg/cig) and 22.8 µg/cig between 1995 and 2007 (range: 11.1 to 32.0 µg/cig): As with current products, yields of FBN were highly correlated with smoke pH.